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cachefiles: make on-demand read killable

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Replacing wait_for_completion() with wait_for_completion_killable() in
cachefiles_ondemand_send_req() allows us to kill processes that might
trigger a hunk_task if the daemon is abnormal.

But now only CACHEFILES_OP_READ is killable, because OP_CLOSE and OP_OPEN
is initiated from kworker context and the signal is prohibited in these
kworker.

Note that when the req in xas changes, i.e. xas_load(&xas) != req, it
means that a process will complete the current request soon, so wait
again for the request to be completed.

In addition, add the cachefiles_ondemand_finish_req() helper function to
simplify the code.

Suggested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-13-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Baokun Li 2024-05-22 19:43:08 +08:00 committed by Christian Brauner
parent 85e833cd72
commit bc9dde6155
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 28 additions and 12 deletions
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38
fs/cachefiles/ondemand.c
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@ -380,6 +380,20 @@ static struct cachefiles_req *cachefiles_ondemand_select_req(struct xa_state *xa
return NULL; return NULL;
} }
static inline bool cachefiles_ondemand_finish_req(struct cachefiles_req *req,
struct xa_state *xas, int err)
{
if (unlikely(!xas || !req))
return false;
if (xa_cmpxchg(xas->xa, xas->xa_index, req, NULL, 0) != req)
return false;
req->error = err;
complete(&req->done);
return true;
}
ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
char __user *_buffer, size_t buflen) char __user *_buffer, size_t buflen)
{ {
@ -443,16 +457,8 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
out: out:
cachefiles_put_object(req->object, cachefiles_obj_put_read_req); cachefiles_put_object(req->object, cachefiles_obj_put_read_req);
/* Remove error request and CLOSE request has no reply */ /* Remove error request and CLOSE request has no reply */
if (ret || msg->opcode == CACHEFILES_OP_CLOSE) { if (ret || msg->opcode == CACHEFILES_OP_CLOSE)
xas_reset(&xas); cachefiles_ondemand_finish_req(req, &xas, ret);
xas_lock(&xas);
if (xas_load(&xas) == req) {
req->error = ret;
complete(&req->done);
xas_store(&xas, NULL);
}
xas_unlock(&xas);
}
cachefiles_req_put(req); cachefiles_req_put(req);
return ret ? ret : n; return ret ? ret : n;
} }
@ -544,8 +550,18 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
goto out; goto out;
wake_up_all(&cache->daemon_pollwq); wake_up_all(&cache->daemon_pollwq);
wait_for_completion(&req->done); wait:
ret = wait_for_completion_killable(&req->done);
if (!ret) {
ret = req->error; ret = req->error;
} else {
ret = -EINTR;
if (!cachefiles_ondemand_finish_req(req, &xas, ret)) {
/* Someone will complete it soon. */
cpu_relax();
goto wait;
}
}
cachefiles_req_put(req); cachefiles_req_put(req);
return ret; return ret;
out: out: